The invention concerns a device for a submersible machine such as a pump or a mixer.
Such a machine normally comprises an electrically driven motor and a hydraulic unit with an impeller connected to the motor via a rotary driving shaft.
In order to prevent the medium within the hydraulic unit from passing along the shaft and penetrating into the motor and causing damage, one or several seals are arranged between the hydraulic unit and the motor. A common type of seal is the so-called mechanical face seal, which comprises one seal ring rotating with the shaft and one stationary seal ring attached to the surrounding pump housing. The two seal rings are pressed towards each other by help of a spring and liquid is thus prevented from penetrating between the two seal surfaces.
If the medium within the hydraulic unit contains pollutants, these may pass between the seal surfaces as the pressure is higher in the hydraulic unit. The seal surfaces may then be damaged and the seal result is jeopardized.
It is therefore necessary to arrange two mechanical seals parted by a room filled with a barrier liquid which cools and lubricates the seal surfaces. In this way the seal close to the motor, called the inner seal, will always operate with a clean medium, thereby diminishing the risks for the seal surfaces being damaged. If the other seal close to the hydraulic unit, called the outer seal, should be damaged, the liquid within said hydraulic unit may penetrate into the barrier liquid room, but by checking the condition of the liquid in said room regularly, the seal can be repaired before any serious damage has occurred. An example of such a design is shown in Swedish Patent No 381 318.
The rotary driving shaft is supported by two bearings, the upper bearing and the lower bearing, the latter being located close to the previously mentioned seal. The bearing, normally a ball bearing, must be lubricated in order to operate satisfactory. It must also be protected from moisture to avoid corrosion of the surfaces of the rings and the balls. If the barrier liquid within the room between the two seals should penetrate through the upper seal, there is a risk that the leakage could destroy the lubrication film and cause a bearing break down.
In order to eliminate this problem it is common to arrange a drainage that expells the leakage from the area and also to provide some sort of protection in front of the bearing. Said protection shall cover the opening between the two bearing rings and prevent leakage from entering and simultanously prevent the grease in the bearing from slipping out. A known protection cover is the so-called NILOS ring. Said device is a ring of sheet metal locked to the outer ring of the bearing by help of a support ring and arranged to cover the opening mentioned. The support ring which is made of a rigid material is sealed relative the bearing housing by help of an O-ring.
A disadvantage with the above mentioned device is that it comprises several details which complicate and make the mounting work more expensive. In addition, there is always a risk that metal shavings may be emitted because of wear which shavings may penetrate into the bearing grease.
The purpose of the invention is thus to obtain a solution to the problem of protecting a bearing from penetrating liquid and particles therein by help of a device which is easy to mount and at the same time runs less risk to become damaged during operation. This is obtained by help of the device stated in the claims.
A sealing washer made of an elastic material for sealing off a ring-formed opening between an inner ring and an outer ring of a ball bearing, the inner ring being mounted on a driving shaft between an electric motor and a hydraulic unit and the outer ring being mounted in a bearing housing, the washer being arranged for preventing outer medium from penetrating into the bearing and simultaneously preventing bearing grease from slipping out of the bearing, the washer comprising a ring-formed body having an outer flange and an inwardly protruding waist for covering the distance between the two rings, the waist including a first contact surface at an inner end thereof, the first contact surface arranged for sliding along the inner ring of the bearing during operation and the outer flange including a second contact surface, wherein when the washer is mounted in the bearing housing, the second contact surface is located mainly radially outside of the outer ring and arranged to make contact with a shoulder on the bearing housing.